System and methods for updating patient registration during surface trace acquisition

Abstract

A surgical navigation system and method for identifying positions on a patient, including a processor, and a tracking system for tracking a pointer tool. The processor is programmed to initialize a surface trace acquisition, continuously record the positions of the pointer tool during the surface, conduct trace acquisition, combine the positions recorded during the surface trace acquisition into a surface trace, receive a patient image of the patient, extract a surface from the patient image, compute a registration transform between the surface traces and the surface for patient registration, segment the patient image into a regions where each region contains an anatomical landmark, determine a spatial distribution of surface traces among the regions; determine whether the spatial distribution in relation to each region minimizes deviance below a threshold, and if the determination is exceeding the threshold, provide information relating to such region.

What is claimed: 
     
       1. A method of performing a patient registration using a surgical navigation system, having a processor, in a medical procedure, comprising:
 initializing a surface trace acquisition; 
 recording one or more surface traces; 
 receiving a patient image of a patient anatomy; 
 extracting a surface from the patient image; 
 computing a registration transform for patient registration between the one or more surface traces and the patient image extracted surface, the patient registration dynamically updated during the surface trace acquisition; 
 segmenting the patient image into a plurality of regions, each region of the plurality of regions containing an anatomical landmark; 
 determining a spatial distribution of surface traces among the plurality of regions; 
 determining whether the spatial distribution in relation to each region of the plurality of regions minimizes deviance below a threshold; and 
 if the spatial distribution in relation to any region of the plurality of regions is determined as exceeding the threshold, providing information relating to such region. 
 
     
     
       2. The method of  claim 1 , wherein computing a registration transform comprises minimizing a set of Euclidean distances or iteratively inputting registration transforms into a cost minimization function. 
     
     
       3. The method of  claim 2 , further comprising:
 initializing a fiducial position acquisition; 
 recording the positions of fiducials on the patient; and 
 receiving the location of fiducials points in the patient image. 
 
     
     
       4. The method of  claim 1 , further comprising the steps of:
 monitoring the position of a pointer tool; 
 analyzing the position to determine if the pointer tool is motionless; and 
 upon determining that the pointer tool is motionless for a predetermined amount of time, prompting the surgical navigation system to initialize or terminate the surface trace. 
 
     
     
       5. The method of  claim 1 , wherein computing a registration transform further comprises:
 receiving input from a user ranking the one or more surface traces; 
 computing a weighting for the surface traces based on the ranking; 
 applying the weighting to the surface traces; and 
 computing a registration transform that minimizes a set of Euclidean distances between the one or more surface traces and the surface. 
 
     
     
       6. The method of  claim 1 , wherein computing a registration transform further comprises:
 receiving input from a user of one or more regions of one or more surface traces to be culled; 
 discarding the one or more regions from the one or more surface traces; and 
 computing a registration transform that minimizes a set of Euclidean distances between the one or more surface traces and the surface after the regions have been discarded. 
 
     
     
       7. The method of  claim 1 , wherein computing a registration transform further comprises:
 initializing one or more landmark acquisitions; 
 recording the positions of one or more landmarks on a patient; 
 receiving the position of one or more landmark points in the patient image; and 
 computing an initial registration transform that minimizes a set of Euclidean distances between the one or more landmarks and the one or more landmark points. 
 
     
     
       8. The method of  claim 7 , further comprising using the initial registration transform to visualize an initial alignment of the patient's position with the patient image in an image space. 
     
     
       9. A surgical navigation system used for navigated surgical procedures, comprising:
 a tracked pointer tool for identifying positions on the patient; a tracking system for tracking the pointer tool; and 
 a processor programmed with instruction to:
 initialize a surface trace acquisition; 
 continuously record the positions of the pointer tool during the surface; 
 trace an acquisition; 
 combine the positions recorded during the surface trace acquisition into a surface trace; 
 receive a patient image of the patient; 
 extract a surface from the patient image; 
 compute a registration transform between the one or more surface traces and the surface for patient registration, the patient registration dynamically updated during the surface trace acquisition; 
 segment the patient image into a plurality of regions, each region of the plurality of regions containing an anatomical landmark; 
 determine a spatial distribution of surface traces among the plurality of regions; 
 determine whether the spatial distribution in relation to each region of the plurality of regions minimizes deviance below a threshold; and 
 if the spatial distribution in relation to any region of the plurality of regions is determined as exceeding the threshold, provide information relating to such region. 
 
 
     
     
       10. The system of  claim 9 , wherein the processor is programmed with further instruction to:
 initialize a fiducial position acquisition; 
 record the position of the pointer tool during the fiducial position acquisition; and 
 receive the location of fiducials points in the patient image. 
 
     
     
       11. The system of  claim 9 , wherein the processor is programmed with further instructions to:
 monitor the position of the pointer tool with the tracking system by recording the pointer tool positions; 
 analyze the pointer tool positions to determine if the pointer tool is motionless; and 
 upon determining that the pointer tool is motionless for a predetermined amount of time, prompt the processor to initialize the surface trace acquisition. 
 
     
     
       12. The system of  claim 9 , wherein the instruction to compute a registration transform further comprises:
 an instruction to receive input, from a user, ranking the one or more surface traces; 
 an instruction to compute a weighting for the surface traces based on the ranking; 
 an instruction to apply the weighting to the surface traces; and 
 an instruction to compute a registration transform that minimizes a set of Euclidean distances between the one or more surface traces and the surface. 
 
     
     
       13. The system of  claim 12 , wherein the instruction to compute a registration transform further comprises:
 an instruction to receive input from a user of one or more regions of one or more surface traces to be culled; 
 an instruction to discard the one or more regions from the one or more surface traces; and 
 an instruction to compute a registration transform that minimizes a set of Euclidean distances between the one or more surface traces and the surface after the regions have been discarded. 
 
     
     
       14. The system of  claim 12 , wherein the instruction to compute a registration transform further comprises:
 an instruction to initialize one or more landmark acquisitions; 
 an instruction to record the positions of one or more landmarks on a patient; 
 an instruction to receive the position of one or more landmark points in the patient image; and 
 an instruction to compute an initial registration transform that minimizes a set of Euclidean distances between the one or more landmarks and the one or more landmark points.